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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 10 5 Feb Meeting ASI / EUMETSAT USER NEEDS… MORE OCCULTATIONS EVENTS  The user requirement of high number of occultation events translates into multi- constellation receiver.  Currently, the rough estimate for a single constellation receiver is ~500 occ/day using rising and setting antennas  Tracking of Galileo SV (when the constellation will be fully deployed) will increase the number to ~ 1000/day  Options to track COMPASS signals, as well as GLONASS may be an interesting opportunity to be evaluated in the near future.  Unclear ICD from COMPASS and future switch to CDMA for GLONASS are uncertain aspects that need to be considered.  Impacts at Rx: Correlator technology (GALVANI, AGGA-4), Number of channels, Processing power

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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 11 5 Feb Meeting ASI / EUMETSAT USER NEEDS…  This requirement translates into better SNR at correlators, good frequency stability in the time interval of an occultation, robust tracking techniques and type signals to be tracked.  On receiver side, better SNR can be achieved by considering good LNA stage on one side (i.e. noise floor reduction) and gain on the antenna side.  Frequency stability in ROSA / ROSA 2° Gen is accomplished by using high-quality USO (currently < min, 1 s) BETTER QUALITY OF OCCULTATIONS: sounding to down to the surface BETTER IONOSPHERIC REMOVAL

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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 12 5 Feb Meeting ASI / EUMETSAT USER NEEDS…  Robust tracking techniques: in parallel to classical closed loop operations, in the last years the focus has been put on open-loop techniques (high-frequency raw sampling).  An implementation of this technique, based on a collaboration between Italian Univiersity (Politecnico di Torino) and TAS-I was already implemented in ROSA  Modernized signals provide the opportunity to deal with pilot signals (i.e., signal components without data bit modulations), forgetting the current problems arosen in removal of Navigation Message Bit in Open Loop (see for example ** ).  Another important advantage of GPS Modernized signals and GALILEO Open Service is the opportunity to access the second frequency without the current drawbacks of L2P(Y) encription. (GPS L2-C, GAL E5a-b, GPS L5) BETTER QUALITY OF OCCULTATIONS: sounding to down to the surface ** S. Sokolovskiy, C. Rocken, D. Hunt, W. Schreiner, J. Johnson, D. Masters, S. Esterhuizen, Inversion of open-loop radio occultation signals at CDAAC, Second GPS Radio Occultation Data Users Workshop, National Conference Center, Lansdowne, VA, 2005 BETTER IONOSPHERIC REMOVAL

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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 14 5 Feb Meeting ASI / EUMETSAT USER NEEDS… LOW LATENCY  This issue impacts more on the ground stations displacement  At the receiver level, one of the possible improvements is to implement a mass memory in order to optimize the exchange with the satellite on-board memory

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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 15 5 Feb Meeting ASI / EUMETSAT STUDY CONTEXT  ROSA 2 nd Generation concept was studied in the framework of a ASI Contract in 2008 (“Opportunity Mission “), with TAS-I acting as a prime contractor  The study was done in cooperation with Italian university for the scientific aspects and user requirements (Università La Sapienza, Tor Vergata, Politecnico di Torino, CETEMPS). Industrial partner (IDS) worked on Instrument feasibility aspects, together with TAS-I  In the framework of ROSA 2° Generation study, a survey of the state of the art technology in GNSS Radio Occultation and Scatterometry from space was carried out.  This allowed the identification of ROSA 2° generation user requirements and tradeoff among various instrument concepts,  The “less mature” scatterometry part (w.r.t RO) was analysed in detail

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All rights reserved, 2008, Thales Alenia Space Navigation Department Page 17 5 Feb Meeting ASI / EUMETSAT 2 Mainly interesting for altimetry applications 1 Elliptical spots to be preferred with respect to circular ones SCATTEROMETRY ANTENNA Due to the fact that we are working in the frame of “mission of opportunity”, also requirements relevant to antenna encumbrance and mass have been considered as “main ones”  A < 0.35m 2 ~ (0.6 x 0.6m) Requirements